(1) Field of the Invention
This invention relates to a release device for a friction clutch for use in automobiles or the like and, more particularly, to a release device in a clutch adapted to be connected and disconnected by a release bearing, of the type in which the release bearing is driven by a cylinder device.
(2) Description of the Prior Art
Hitherto, there has been known a friction clutch in which a cylinder device for driving a release bearing is disposed adjacent the release bearing in a clutch housing.
According to such arrangement, the cylinder is formed with a cylindrical operation chamber therein and a cylindrical piston fits in the operation chamber. The piston projects outwardly from one end of the operation chamber, the projecting end of the piston being connected to the release bearing. The piston has an annular rubber packing secured to its end within the operation chamber through the intermediary of a concave-convex fitting portion so as to prevent leakage of operation liquid from the operation chamber.
With the above arrangement, however, it is inevitable that the piston tilts slightly relative to the cylinder during operation so that the packing-mounted end of the piston may shift radially. The packing, which is secured to the piston through the concave-convex fitting portion, may get out of position or become distorted when the piston shifts as above mentioned, with the result that the desired sealing function cannot be obtained.
The packing is merely fitted on the piston at the concave-convex portion and is not securely fixed by adhesive or the like to the piston. Therefore, when the operation chamber is not in pressurized state, the packing may become separated from the piston, and if, when the packing is in such separated condition, the operation chamber is pressurized whereby pressure is applied to the packing, the pacing may, in an extreme case, fall down or get so deformed that it is even turned over.
Further, despite the provision of such packing or seal, it may not be possible to positively prevent the operation liquid within the operation chamber from leaking outward, in trace amounts, though, passing through the clearance between the piston and the cylinder. If such leakage occurs, the liquid may adhere to the facing of the clutch, with the result that clutch slippage or judder may be caused.
A liquid pressure control passage pipe for supply of liquid pressure to the operation chamber is connected to the cylinder. A seal for the joint between the pipe and the cylinder may be deteriorated by heat or otherwise, which may result in poor sealing function.
A further problem is that assembly work for the joint is rather difficult because the pipe must be fixed to the cylinder while a predetermined compressive force is applied to the seal.
The object of the invention is to provide a release device for a clutch which eliminates the foregoing problems.